Detailed explanation of types of electric tools and safety precautions

In the 1960s, with the development of battery manufacturing technology, a batteryless power tool with a power cord that uses a nickel-cadmium battery as a power source has emerged. However, it was slow to develop because of its high price. In the mid to late 1970s, due to lower battery prices and shorter charging times, this type of power tool was widely used in Europe, America and Japan. Electric tools were originally cast iron shells, and later used as aluminum alloy shell. In the 1960s, thermoplastic engineering plastics were used in power tools and achieved double insulation of power tools, which ensured the safety of power tools. Due to the development of electronic technology, electronic speed control power tools also appeared in the 1960s. This kind of power tool uses thyristors and other components to form electronic circuits and adjusts the rotation speed by the depth at which the switch knobs are pushed in, so that when the power tool is used, the power tools can be different according to the objects to be processed (such as different materials, sizes of drill holes, etc.). ), choose a different speed.

species:

Power tools are mainly divided into metal cutting power tools, grinding power tools, assembling power tools and railway power tools. Common power tools include electric drills, electric grinders, electric wrenches and electric screwdrivers, electric hammers and impact drills, concrete vibrators, and electric planers.

1 Electric drill: The main specifications are 4, 6, 8, 10, 13, 16, 19, 23, 25, 32, 38, 49mm, etc. The figure refers to the maximum diameter of the drill bit drilled on the steel material with a tensile strength of 390N/mm. . The maximum drilling diameter for non-ferrous metals, plastics and other materials can be 30 to 50% larger than the original specification.

2 Electric grinder: A tool for grinding with a grinding wheel or disc. There are straight electric grinders and electric angle grinders.

3 Electric wrenches and electric screwdrivers: Used for loading and unloading threaded couplings. The drive mechanism of the electric wrench consists of planetary gears and ball screw groove impact mechanism. Specifications include M8, M12, M16, M20, M24, M30, etc. Electric screwdriver adopts claw clutch transmission mechanism or gear transmission mechanism, specifications M1, M2, M3, M4, M6 and so on.

4 Hammer and Impact Drill: Used for drilling, grooving, and roughing of concrete, brick walls and building components. The use of expansion bolts can increase the installation speed and quality of various pipelines and machine tools. The impact principle of the hammer is to generate impact power by the internal piston movement. The impact principle of the impact drill is that the gears run into impact power, so the impact of the hammer More powerful.

5 Concrete Vibrators: Used to pour concrete when pouring concrete foundations and reinforced concrete components to eliminate air holes and increase strength. The high-frequency disturbance force of the electric direct-coupled vibrator is formed by the motor driving the eccentric block to rotate, and the motor is powered by a 150 Hz or 200 Hz intermediate frequency power supply.

6 Electric Planer: Used for planing wood or wooden structure parts. It can also be used as a small planer on a bench. The blade of the planer is driven by the motor shaft through the belt.

Power tool safety protection:

Class 1I tool safety protection:

There is a grounding device in the tool, and all or most of the insulation structure has basic insulation. If the insulation is damaged, the accessible metal part is connected to the protective ground (see ground) or the protective zero wire installed in the fixed line through the grounding device. It will not become a live body and can prevent the operator from getting an electric shock.

2 class II tools security protection:

The insulation structure of such tools consists of double insulation or reinforced insulation consisting of basic insulation and additional insulation. When the basic insulation is damaged, the operator is separated from the live body by the additional insulation, and no electric shock is caused. Class II tools must use non-reconnectable power plugs and must not be grounded.

Class 3 III tool safety protection:

This type of tool is powered by a safe voltage source. The effective value of the no-load voltage between the safety voltage guide body or between any conductor and the ground shall not exceed 50V; for the three-phase power supply, the effective value of the no-load voltage between the conductor and the neutral line shall not exceed 29V. The safety voltage is usually supplied by a safety isolating transformer or a converter with a separate winding. No protective grounding device is allowed on class III tools.

4 Radio interference suppression:

A single-phase series motor with a commutator and a direct current motor can cause serious electromagnetic interference to televisions and radios. Therefore, electric tools must be designed to take into account radio interference. The main use of shielding, excitation winding symmetrical connection, set the electrical filter, filter connected into â–³ shape and other measures. If necessary, small inductance coils can also be connected in series at both ends of the motor armature.